The present invention relates to a variable displacement swash plate type compressor adapted for use in an air conditioning system for a vehicle, and more particularly to a compressor having a passage providing fluid communication between an oil sump and a crank chamber, and a spray nozzle disposed at the crank chamber end of the passage for efficiently distributing a fine mist or spray of lubricating oil to the crank chamber.
A typical conventional variable displacement swash plate type compressor includes a cylinder block provided with a number of cylinders, a piston disposed in each of the cylinders of the cylinder block, a crankcase sealingly disposed on one end of the cylinder block, a cylinder head sealingly disposed on the other end of the cylinder block, a rotatably supported drive shaft, and a swash plate. The swash plate is adapted to be rotated by the drive shaft. Rotation of the swash plate is effective to reciprocatively drive the pistons. The length of the stroke of the pistons is varied by the inclination of the swash plate. Inclination of the swash plate is varied by controlling the pressure differential between a suction chamber and a crank chamber. Lubrication of components within the crankcase is typically provided by circulating refrigerant gas mixed with lubricating oil within the internal refrigerant circuit of the compressor. Typical conventional variable displacement swash plate type compressors may also use carbon dioxide (CO2) as the refrigerant gas.
Another conventional lubricating system disclosed in the prior art employs lubricating oil passageways separately arranged from the refrigeration circuits. The separately arranged oil passageways avoid reduction in the refrigerating efficiency of a refrigeration circuit in a vehicle caused by an attachment of the lubricating oil to an evaporator of an air conditioning system. For example, lubricating oil may be pumped by a gear pump through a lubrication passage and radial branch passageways within the drive shaft to lubricate the moving components within the crank chamber.
The compressor arrangements in the prior art described above in which CO2 is used as the refrigerant gas have several disadvantages. First, because conventional lubricating oil is not soluble in CO2, the lubricating oil cannot be effectively distributed with the CO2 as the CO2 is circulated within the internal refrigeration circuit, resulting in ineffective lubrication of the close tolerance moving parts within the crank chamber. Second, in a compressor having separately arranged lubrication passages, the lubricating oil is subjected to a gradual pressure drop while flowing inside the lubrication passages. The volume of the oil flowing out of the branch passageways furthest from the gear pump is caused to become less than the volume of oil flowing out of the branch passageways nearest the gear pump. In such an arrangement lubricating oil is not efficiently and effectively distributed within the crank chamber.
An object of the present invention is to produce a swash plate type compressor wherein oil flow to the crankcase during both minimum and maximum operating conditions is improved to result in efficient lubrication of the compressor components.
Another object of the present invention is to produce a swash plate type compressor wherein lubricating oil can be efficiently and evenly distributed within the crank chamber.
The above, as well as other objects of the invention, may be readily achieved by a variable displacement swash plate type compressor comprising: a cylinder block having a plurality of cylinders arranged radially therein; an oil sump for containing lubricating oil; a piston reciprocatively disposed in each of the cylinders of the cylinder block; a cylinder head attached to the cylinder block; a crankcase attached to the cylinder block to define a crank chamber; a drive shaft rotatably supported by the crankcase and the cylinder block; a swash plate adapted to be driven by the drive shaft, the swash plate having a central aperture for receiving the drive shaft; a pump for distributing the lubricating oil from the oil sump to the crank chamber; a lubrication passage providing fluid communication between the oil sump and the crank chamber; and a spray nozzle disposed at the crank chamber end of the lubrication passage for facilitating distribution of lubricating oil to the crank chamber.